Project Abstract The prevalence rates of adolescents' obesogenic behaviors are alarming, and reduced life expectancy is the future of America's youth if behavioral changes are not implemented to improve health and reduce the obesity burden. Approximately 69% and 73% of adolescents do not consume daily recommended fruits and vegetables respectively, while 53% engage in insufficient physical activity. These behaviors magnify risks for obesity-related disease burden in adolescence and adulthood including type 2 diabetes, rates of which have increased markedly among adolescents and young adults. Reversing obesity trends requires emphasis on prevention with novel and sustainable intervention strategies to address adolescents' obesogenic behaviors. Predictive theoretical models suggest that health knowledge works in conjunction with motivation and behavioral skills to influence adolescents' obesogenic behavior. However, most existing adolescent interventions target these variables in isolation. Further, health literacy (HL), a precursor to health knowledge, is necessary for translating health knowledge into behavior and is negatively related to adolescents' obesity status. HL is the ability to access, understand, and utilize health information to make informed health decisions. It includes four categories: functional (reading, writing, and numeracy skills), interactive (use health knowledge to communicate and interact with others and environment), critical (advocate for self/others through action), and media (critically analyze health-related media). Yet, HL has not been included in interventions targeting adolescents. We hypothesize that the inclusion of HL into evidence-based interventions will increase intervention effectiveness and behavioral outcomes. Our long-term goal is to reduce the incidence of obesity and chronic disease risk in adolescents through interventions that address individual and contextual factors related to long-term health decision-making and behavior change. The goal of the proposed study is to pilot test the effectiveness of adding a HL module to an obesity prevention intervention that addresses adolescents' obesogenic behaviors. For Aim 1, we will modify successful components from established obesity interventions into an interactive digital platform with and without HL modules. We will test the intervention for accessibility and usability among adolescents 14-16- years-old and modify and retest the intervention iteratively until it is acceptable to adolescents. For Aim 2, the intervention will be piloted among 76 adolescents in a two-arm randomized-controlled-trial to assess preliminary effectiveness and feasibility. The major innovations of the study are the inclusion of HL, a potentially critical factor in adolescents' obesogenic behaviors, and the use of an interactive digital platform for the intervention. We anticipate that the results of this pilot study will lay the groundwork for a future large-scale clinical trial to test the effectiveness of the inclusion of HL on interventions for diverse groups of adolescents.